The present invention is an improved elevator rail system and method for constructing and installing the same.
In elevator systems, a car is vertically displaceable between floor, and is guided for vertical movement in a hoistway. The conventional and industry standard means for guiding an elevator is with a "T" section rail supported from the building structure and sliding shoes or a series of wheels known as roller guides mounted on the car.
A conventional T section rail 10 is shown in FIG. 1 and labelled as "prior art". The guiding surfaces 12, 14 and 16 normally machined to provide a smooth surface and to maintain straightness and proper size. In typical building constructions, the rail system is constructed from a plurality of rail sections, and the end faces between the adjacent rail sections must be carefully machined to assure alignment and structural continuity between rail sections on the respective adjacent surfaces 12, 14 and 16. This is normally done with an interlocking connection between the ends of the respective rails, and a backing plate between rails. As shown in FIG. 1, the top surface 18 of rail 10 is machined to have a tongue 20, which provides an interlocking connection with a corresponding groove machined in the rail section to which section 10 is to be connected. The backing plate 22 bolts to a machined surface 24 on the back of the rail 10 and, when rail sections are joined, is bolted to a similar machined backing surface on the adjacent rail.
This system is functionally adequate and is presently the industry standard for elevator systems. However, this type of system is both expensive to produce and time consuming and costly to install. The high cost of production results from the extensive machining which is required in producing the rail systems, as described above. The installation costs stem from three sources.
First, the rail system must be aligned in three ways: (1) the rails must be aligned plumb (precisely vertical); (2) the rail system must be maintained a precise distance from the rail on the opposite side of the hoistway; and (3) the rail system must be given precise angular alignment relative to the hoistway and relative to the other rail system. In other words, the surfaces 12, 14 and 16 must be oriented at the correct angle relative to the hoistway and opposite rail system for properly receiving the sliding shoes or rollers on the car. This alignment requires the use of expensive support brackets attached to the building structure, ones that will allow freedom of adjustment, and also requires extreme care on the part of the installer.
Second, because a backing plate 22 and multiple bolting are required at the splices between rail sections, these splices take up considerable space in the hoistway. The splices often interfere, or compete for position with, other supports on the building structure.
Third, the need for machined portions at the facing surfaces between rail sections, for example tongue and groove sections formed on respective facing surfaces, greatly limits the use of scrap pieces. When a machined rail section is cut during installation, it will no longer have a properaly machined tongue or groove at the cut end. This creates the need for maintaining a variety of machined lengths and consequently increases the necessary inventory of pieces.